Spray gun



J y 6, 1940- A. I. LOGETTE ET AL 8, 6 I

SPRAY GUN Filed Jul 19, 1938 Patented July 16, 1940 j UNITE]? STATES PATENT OFFICE.

SPRAY GUN Abraham Isaac Logette and Edgar Harry Dainton,

London, England Application July 19, 1938, Serial No. 220,070 In Great Britain July 21, 1937 Claims. (Cl. 299-140) This invention relates to apparatus for sprayand outlet passages for the liquid to be sprayed ing liquids-such asoils, paints, varnishes and so and is closed at its other end by a perforated forth, under pressure, of the kind known as spray cover through which works a piston rod mounted guns, and has for its object to provide such spray upon the piston that works in such cylinder.

5 guns with a new and improved measured quan- The adjustable liquid supply valve is mounted 6 tity delivery device which enables the volume of in a housing formed or arranged upon the body liquid to be sprayed at each operation of the gun or the spray gun, which housing is connected to be accurately controlled and indicated to the with the inlet passage of the cylinder and also operator. with the liquid supply system, of the spray gun The present invention is particularly applicathrough the inlet valve mounted therein, which 10 ble to spray guns such as those employed for valve is spring controlled and furnished with an spraying mixtures of oils and other liquids and operating lever while the liquid outlet passage of anti-corrosive solutions into the cylindersof aerthe cylinder is connected with the delivery tube oplane and other engines to form a protective of the spray gun which tube is normally closed film and enables the volume of the sprayed liquid in known manner by a spring controlled delivery at each operation of the gun to be accurately devalve through which it is connected to the spraytermined and indicated to the operator. ing head of the gun. i

Spraying guns of the kindreferred to are pro- The rod of the piston that works within the vided with a connection to the source of liquid cylinder serves to indicate the volume of liquid to be sprayed which is stored at suitable presadmitted to and discharged from the cylinder. 20 sure and with a valve controlled connection For this purpose such rod may be furnished with with an air compressor or other suitable source a suitable scale or it may cooperate with an adof motive fluid, the liquid to be sprayed being justable stop mounted upon a graduated guide delivered to the gun under compressed air or arranged externally of the cylinder.

other pressure and forced through the spraying The piston of the measured quantity delivery, 25 head by the compressed air or other motivefiuid, apparatus may be spring controlled, alternatively the supply of which is regulated by the comsuchpistonmay be controlled by compressed'air pressed air or other motive fluid valve controlled admitted to the cylinder through an air passage by th operator, connected with the compressed air-circulating According to this invention agun for spraying passages of the spray gun. 30 liquids under pressure is provided with a meas- Such compressed air passages are controlledby ured quantity delivery and indicating apparatus a normally closed air'valve which is connected that is connected through an inlet valve with the through such'passages on one side with a source supply of liquid to be sprayed and also through of compressed air and on the other side with the an outlet with the spraying head or nozzle of the spraying head of the gun through passages ar- 35 gun so that the measured quantity delivery apranged concentrically of the liquid delivery tube,

paratus can be charged under pressure with the which latter is interconnected with the concentric liquid to be sprayed and forms the reservoir air passages so that when the gun is operated the from which such liquid is supplied under pressure liquid is sprayed through such head by the com- 40 to the spraying head through which it is sprayed pressed air. 40 in known manner by the compressed air or like The spray gun is operated through its main motive fluid controlled by the operator, while operating lever which is connected with the liqmeans are preferably provided for by-passing or uid delivery valve and arranged relatively to the rendering inoperative the measured quantity deair valve so that both valves are operated tolivery apparatus so as to enable the gun to be gether by the lever. The liquid to be sprayed is 45 used for spraying liquid independently thereof. delivered from the cylinder by the pressure-con- The measured quantity delivery and indicating trolled piston mounted therein past the liquid apparatus comprises a cylinder of predetermined delivery valve as the latter is opened, while comcapacity formed or arranged upon the body of pressed air 'passesthe air valve through the air the spray gun, a pressure controlled piston which passages to the spraying head in which it mingles 5 works fluid tight therein and an adjustable liquid with the liquid and sprays the same theresupply valve through which the cylinder is through. f 7 charged under pressure with the liquid to be The invention'is further described with refersprayed. ence to the accompanying drawing wherein simi- The cylinder is furnished atone end with inlet lar references indicate like parts. 55

- fied construction of the measured quantity delivery apparatus and Fig. 4 a sectional view illustrating a further modification thereof presently referred to.

Referring to the drawing, in the constructions V v illustrated the cylinder I and the valve housing 2 of the measured quantity delivery apparatus are formed integrally with the body'3 of the spray gun. One end of the cylinder is connectedby an inlet passage .4 with the valve housing and also by an outlet passage 5 with the liquid delivery tube of the spray gun, presently referred to. A piston 6 furnished with a piston rod l is slidably mounted in the cylinder I, the outer end of which is closed by a perforated cover 8 through which the piston rod works, such cover having an externally threaded flange 8a which screws into'the internally threaded outer end of the cylinder.

The piston- 6 is furnished on its inner side with a cup leather 6a which makes 'a' slidingfluidtight joint with'the interior of the: cylinder and is se cured on the reduced screw threaded end of the piston rod la by a-washer 6band nut lb.

In the construction illustrated in Fig.- 1 the pistonis controlled by thepressure of two coiled springs which-are mounted upon the piston rod soas to bear between the piston fi and the per-' forated "cylinder cover 8'Whi1e the reduced end la of the piston rod is adapted' to abut the inner end of the cylinder so as to limit the inward movement of the piston therein.

The cylinder cover 8 is formed with an'external graduated rack H of channel cross-section, the

- side walls 12 of which have regularly spaced notches Ha formed therein which are indexed. to form a volumetric scale and are adapted to receive an adjustable stop 1211. Such stop consists er a cross-bar mounted in the limbs of a fork "l3 that comprises a socket I4 in-which a springcontrolled bullet catch-l5 is mounted so as to b'ear on the underside of the rack andhold' the stop in engagementtherewith.

Thecylinder lismade ofpre-determined cap'a'city and the scale of the rack ll calibrated therewith so that the" movementsof the piston rodover'such scale indicate. the volume ofiliquid admitted or displaced by the corresponding movements of the piston 6- in the cylinder.

. Thevalve housing 2 is furnished with 'ac'oned liquid supply'valve l6' which controls an inlet passage 2a in such housing and is provided 'with valve-is controll'ed by a coiled-spring l8 mounted upon its spindle'between-Ithe'guide' I l and the stuffing box IE secured inthexupp'er end of the housing by a perforated screw gland 20 through '65;

whichtheval-ve spindle projects and works. The

' outer end'of the valve spindle isscrew threaded and passes through the perforated arm 'ZI of an operating lever22 in which the" valve spindle is adjustably retained by nuts Zia-while the lever 2-2 is 'pivotally'm'ou'nted upon :aspindle 23 in bearings 23aformed orr the exteriorof the valve housing. I

The body- 3 of the spraygun comprises as usual a-pisto'n grip extension to and a'barrel 24 inwhich .'-a liquid deliverytube 25fzis mounted .concentri a spindle I605 and a grooved guide I1. Such,

cally so as to form an annular space 24a in the barrel.

As shown, the delivery tube is screwed into a reduced internally threaded extension 2411 of the barrel,- while its outer end is furnished with a nozzle piece 26 that forms a housing for a coned liquid delivery valve 21, controlled by a coiled spring 28 so that it normally closes the vent of the nozzle piece. 7 The outer end of the gun barrel 24 is furnished with an externally threaded coupling tube 29 one end of which is secured fluid tight therein by a nut-29a and packing 2% while its other end carries anadjustably mounted internally threaded union nut 38 which is adapted to connect the delivery pipe 3| that leads to the spraying head 32. In the construction illustrated the delivery pipe 3| is of light metal and is provided with an internal liquid outlet pipe 33 of small diameter which is retained concentrically therein by spiders or perforated distance pieces a so as to form an annular air space about the centre pipe.

The outer delivery pipe 3! is furnished with a flange 38a at its inner end while the small inner delivery pipe 33 projects beyond the flange 3| to form a spigot 3'3a, its' other end terminating within the spraying head 32 (Fig. 2) so that it intercommunicates with the terminal end of the annular air space 3m in such head.

The spigot end 33a of the liquid outlet pipe 33 is adapted to engage a socket 26a formed in the adjacent end of the nozzlepiece 26 as an extension of the nozzle vent that is normally closed by the liquid'delivery valve- 21.

The liquid delivery valve is connected to the operating lever 35 of the gun by the valve rod 34 and U-shaped bridle 35. The operating lever is controlled by a spring 31 and provided with an adjustable set :screw 38 for operating the normally closed spring controlledair valve 39 that is mounted as usual in the body of the spray gun so as to control air passages 40 and 40a formed therein.

The air inlet passage 40 is furnished with a coupling 4| through which it is connected with the oompressed'air supply pipe from the compressor or other suitable source of compressed aiig 'while the air passage 40a connects the air valve with the barrel 24 of the gun.

The body of the gun is alsofurnished with a liquid inlet passage 42 furnished with a coupling 43 by which it is connected with the supply pipe to the source of liquid tobe sprayed, the inner end of which passage is connected by a liquid supply duct 42a with the inlet 2a in the valve housing 2' of the measured quantity delivery apparatu's, which inlet 20: is normally closed by the spring controlled liquid supply valve l6 mounted in such housing. The outlet passage 5 of the cylinder l is interconnected with the liquid delivery tube 25 in the barrel of the gun, which tube is normally closed bythe liquid delivery valve 21.

-The measured quantity delivery cylinder l is charged under pressure with the liquid to be I sprayed by operating the lever 22 of the liquid supply valve I6'to allow the liquid to flow through the valve housing 2 into the cylinder and move forward the piston 6 against the resistance of its controlling spring, the liquid also priming the delivery tube 25 and nozzle piece 26, closed by the liquid delivery valve 2?.

As the piston'moves forward the outer end of the piston rod 1 moves over the graduated rack H until its abuts the adjustable stop set in one or other of the-rack notches; so automatically the air valve 39 in the gun body. As these valves are opened the liquid to be sprayed is driven I from the measured quantity cylinder l by the pressure controlled piston '6 mounted therein through the liquid'delivery system of the gun to the spraying head, while compressed air is also admitted past the air valve through the annular space 24a; in the gun barrel and the restricted annular space 111' about thenozzlepiece 26 through the annular air passage in the delivery pipe 3| to the spraying head, in which latter the compressed air mingles with theliquid and delivers the same through the spraying head as a fine spray. i

The measured quantity delivery oylinderl is furnished with an air vent that is normally sealed by a screw plugiin which is opened when the cylinder is being charged to allow any air trapped behind thepiston and in the liquid delivery system to 'escapa'the plug being reolosed immediately thereafter.

If desired, the measured quantity delivery apparatus may be rendered inoperative by locking the liquid supply valve l6 thereof in its open position. To effect this the nuts Zla on the outer end of the valve spindle I60. are screwed up so as to raise thespindle in the perforated arm 2| of the operating lever, which prevents the valve closing the inlet 2a of the valve housing 2. The liquid to be sprayed thus passes via the valve housing, the inlet passage 4 and outlet passage 5 of the cylinder l to the liquid delivery tube 25 in the barrel of the gun so that the latter can be used in the ordinary way for spraying liquid independently of the measured quantity delivery apparatus. Alternatively, the spraying apparatus may be provided with means for by-passing the measured quantity delivery apparatus, such for example as a direct connection between the liquid and delivery passages of the apparatus, such connection being controlled by a by-pass valve.

In the modification illustrated in Fig. 3 the piston rod 1 is shown furnished with a volumetric scale which registers against the outer surface of the cylinder cover 8 as the liquid to be sprayed is admitted to and discharged from the cylinder I, this arrangement being used in place of the graduated rack and stop described with reference to Fig. 1.

In the modification illustrated in Fig. 4 the piston 6 in the measuring cylinder I is controlled by air pressure instead of by springs. For this purpose the perforated cylinder cover 8 is furnished with a gland and stufling box through which the piston rod I works fluid tight, while the cylinder l is provided with a compressed air inlet passage Id, which is arranged adjacent to the cylinder cover and communicates with the concentric air space 26a in the gun barrel 24. The piston 6 is provided on its front surface with an additional cup leather 60 which makes a sliding fluid tight joint with the cylinder to prevent escape of motive fluid past the piston. The piston 6 is externally grooved as indicated at 6:1: and furnished with a cross passage 6y which oommunicates with a longitudinalbore in: formed through the piston rod 1 so that any motive fluid leaking past the piston F6 can escape through the passage 6m, By and 1:1: to the atmosphere. In this construction, when the cylinder 1 is charged under pressure with the liquid to be sprayed, the piston 6 is moved forward and displaces air trapped therein through the air passage 'ld.

When the lever =36 of the spray gun is operated compressed air is supplied to :the cylinder l in front of the piston 6 through theair. passage Id so that the piston is driven back and displaces under pressure the'liquid to be sprayed'through the outlet passages tothe spraying head, as previously described.

What we claim is:

1. The combinationwith'a gun for spraying liquids, of a'measured quantity delivery and indicating apparatus comprising a'cylinder of predetermined capacity furnished withliquid inlet and outlet passages, a pressure controlled piston working fluid tight insaid cylinderand provided with a piston rod adapted to indicate the volume of liquid admitted to anddischarged from said cylinder and liquid supply valve through which said cylinder is charged under pressure. with the liquid to be sprayed and'an' outlet passage connecting said cylinder with the liquid delivery valve of the spray gunthrough which the liquid is delivered to' the spraying'head, said piston working within the cylinder being adapted to coact with an adjustable stop mounted upon a graduated guide arranged externally of the cylinder so as to limit and indicate the volume of liquid admitted to and discharged from said cylinder through the spraying head.

2. The combination with a gun for spraying liquids under pressure of a measured quantity delivery and indicating apparatus comprising a measuring cylinder having at its inner end an air vent furnished with a plug and liquid inlet and outlet passages through which said cylinder is arranged in series with the liquid inlet and delivery system of the spray gun, said inlet passage being connected with said liquid inlet system through a normally closed spring controlled liquid supply valve and said outlet passage with said liquid delivery system which is normally closed by the delivery valve of the gun and connected with the spraying nozzle, a piston working fluid tight in said measuring cylinder and furnished with a piston rod that works through a perforated cover on the outer end of said cylinder, a tail rodon said piston adapted to abut the inner end of the measuring cylinder and limit the inward movement of the piston therein, a graduate guide mounted externally of said cylinder cover and a stop adjustably mounted on said guide in alignment with the piston rod to limit the outward movement of said piston and rod under the influence of liquid supplied to the cylinder through said liquid supply valve, and means for supplying pressure to the piston so as to return the piston in the cylinder and force the liquid from the latter to the spraying nozzle of the gun when the latter is operated.

3. In a gun for spraying liquids under pressure furnished with a measured quantity delivery and I liquids under pressure, of a measured quantity 7 delivery and indicating'apparatus comprising a measuring cylinder, inlet and outlet passages. at the inner end of said cylinder arran'ged in series With the liquid inlet and delivery system of the gun, an adjustable springcontrolled liquid supply valve in series with said liquid inlet passage, means for holding said valve open, a piston working fluid tight ins'aid cylinder and furnished with a piston rod that. works fluid tight through a perforated cover on the outer end of the cylinder, said piston being externally grooved and furnished with a transverse bore communicating with said groove and with a longitudinal bore in said piston rod, an air passage in the outer end of said cylinder adjacent the cover thereof, which passage constantly communicates with the compressed air circulating systemdof the spray gun so that when the latter is operated the piston is moved inwards to expel liquid from the cylinder to' the spraying head of the "gun, a volumetric scale on said piston rod adapted to read against theouter surface of the cylinder cover through which it works,adjustable means externally of said cover to limit the. outward movement of said piston and piston rod in said cylinder, and an air ventfurnished with an adjustable plug on the inner end of said measuring cylinder.

"5.'In a paint spray gun or the like, a pistol like body enclosing a piston chamber and a valve chamber and having a pistol-grip extension, a piston in said piston chamber, a piston rod carrying, said piston and extending beyond the same at one side to form a stop, a spring to force said piston in the direction of the stop, said body having a port between said valve chamber and said piston chamber, a. liquid inlet port to said valve chamber and a spring-loaded valve controlling said liquid inlet port, a lever for opening said valve, means to indicate the position of said piston in its cylinder, an adjustable stop to limit the movement of said piston away from the liquid inlet end of the cylinder, a liquid delivery tube in communication with the liquid inlet end of said cylinder, a spring-loaded valve normally closing said delivery tube, a compressed air duct cooperatively associated with said delivery tube, a spring-loaded valve controlling the passage of air through said compressed air duct, and a single lever means cooperately associated with said pistol-grip extension and connected with said compressed air valve and with said delivery tubes valve for simultaneously opening both said valves.

ABRAHAM ISAAC LOGETTE. EDGAR HARRY DAINTON. 

